HP Demonstrates Glasses-Free 3D Display


HP has published details on technology that could use ‘directional pixels’ to make 3D displays possible in mobile devices such as smartphones and tablets

HP Labs on Thursday published details of a new type of display that it said could finally project 3D images of the kind seen in the 1977 film Star Wars.

The display, a paper on which was published in the latest edition of the scientific journal Nature, would not need moving parts or special glasses to work, and in theory permits a viewing angle of up to 180 degrees.

Full 3D

That means a viewer could walk around the display, viewing the projected image from as many as 200 different viewpoints for still images, or 64 viewpoints for 30-frames-per-second of video, according to HP’s researchers. 3D imaging of the kind used in the cinema, or in devices such as LG’s 3D-capable smartphones, provides only one viewpoint.

nature11972-f1.2And because the technology is based on existing LCD displays, it should be thin and light enough to be suitable for mobile devices such as watches, smartphones and tablets, HP said.

The display uses a “multi-directional diffractive backlight technology that permits the rendering of high-resolution, full-parallax 3D images in a very wide view zone (up to 180 degrees in principle) at an observation distance of up to a metre,” HP said in the paper.

The invention, created by researchers at HP Labs in Palo Alto, California, uses a transparent screen surrounded by light-emitting diodes (LEDs), the same basic technology used in standard LCDs.

However, while the screens found in current LCDs contain randomly patterned pixels to scatter white light through the display’s colour filters, polarisers and shutters, HP’s screen uses deliberately patterned “directional pixels” that control the light. This allows the display to send slightly different images to each eye, the basis for the 3D effect.

“The key to our design is a guided-wave illumination technique based on light-emitting diodes that produces wide-angle multiview images in colour from a thin planar transparent lightguide,” HP’s researchers wrote in Nature. “Pixels associated with different views or colours are spatially multiplexed and can be independently addressed and modulated at video rate using an external shutter plane.”

A prototype built by HP Labs can display moving images with 64 possible viewing angles, with a spatial resolution of 88 pixels and a viewing zone of 90 degrees. Other hand-held prototypes are described that show animated sequences of up to six 200-view images at a resolution of 127 pixels per inch.

One problem is providing the actual imagery for all these different points of view, something which could limit true 3D to computer-generated images.

HP researcher David Fattal, who led the work, suggested the technology could be used to display synthetic images such as Google Maps or architectural models on a tablet or smartphone.

“If you were to display a 3D image of planet Earth with the north pole facing out of the screen, by turning your head around the display you’d be able to have a view of any country on the globe,” Fattal told the Guardian.

HP researcher Raymond Beausoleil said other applications could relate to 3D signage for mobile devices, or the visualisation of complex data or of molecular configurations for pharmaceuticals.

In an article accompanying the paper, Neil Dodgson, professor of graphics and imaging at Cambridge University’s Computer Laboratory, said the display could represent an “exciting alternative to current solutions for mobile devices”, though he cautioned that there is “considerable work to be done” for quality to be improved to an acceptable level.

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